1. Field of the Invention
The present invention relates to an inkjet recording medium and a method of manufacturing such a medium.
2. Description of the Related Art
With recent rapid advances in the information-technology industry, a wide variety of information-processing systems have been developed, and recording methods and apparatus suitable for respective uses in those information-processing systems have also been developed and put to practical use.
Of those recording methods, an inkjet recording method has been widely adopted not only in offices but also for the so-called at-home recording because of its advantages that it allows recording on various kinds of recording materials and the hardware (apparatus) required thereby is relatively inexpensive, compact and extremely quiet.
In addition, as the resolution of images printed by inkjet printers has been enhanced in recent years, it has become possible to obtain records of the so-called photograph-like high quality, and with such an evolution of the hardware (apparatus), various kinds of inkjet recording media have been developed.
In general, the properties required of recording sheets for inkjet recording use include properties of (1) ensuring quick drying of ink (absorbing ink with great speed), (2) ensuring ink dots of correct and uniform diameter (being free of bleeding), (3) ensuring good graininess, (4) ensuring highly round ink dots, (5) ensuring high color densities, (6) ensuring high saturation (no dullness), (7) ensuring high resistance to water, light and ozone in the printed portion, (8) having high whiteness degree in the background portion, (9) having good storability (causing neither yellow coloration even upon long-term storage nor bleeding of images by long-term storage (bleeding with age)), (10) having high resistance to deformation and good dimensional stability (being minuscule in curling), and (11) ensuring smooth running in apparatus.
When recording sheets are used as glazed photo paper for the purpose of obtaining the so-called photograph-like high-quality records, they are further required to have glossiness, surface smoothness and texture resembling that of photographic printing paper for silver-salt photograph in addition to the properties recited above.
With the aim of improving those properties, inkjet recording media having porous structures in their respective ink-receiving layers have been developed and put to practical use in recent years. By having porous structures, such inkjet recording media can have excellent ink receptivity (quick-dry properties) and high glossiness.
For example, the inkjet recording media each having on a substrate an ink-receiving layer containing fine particles of inorganic pigment and a water-soluble resin, thereby having a high porosity, have been put forth (See, e.g., JP-A Nos. 10-119423 and 10-217601).
Owing to their makeup, those recording media, notably the inkjet recording medium provided with an ink-receiving layer having a porous structure using silica as fine particles of inorganic pigment, have high ink absorbency and ink receptivity high enough to form images of high resolution, and can show a high gloss.
On the other hand, among ingredients incorporated into an ink-receiving layer, sulfur compounds are known as a component capable of improving ozone resistance (See, e.g., JP-A Nos. 2002-96546, 2003-285535 and 2006-321176).
However, there are cases where incorporation of sulfur compounds into ink-receiving layers causes reduction in image density.